Hi Zhiyan,

There are a lot of different Au-Sn solder bump types:
- evaporated Au and Sn multilayer bumps resulting in thin solder layers
because it is hard to evaporate thicker gold layers and due to lift-off
techniques used.
- electroplating of Au and Sn from composite bath (requires strict bath
composition control and puls plating conditions)
- electroplating a stack of two layers of Au and Sn in seperate baths
(that is what we prefer and there we can determine the solder amount on
top of the Au socket by the deposited Sn height).

You may also find different under bump metallizations. Finally you
should select the technology according to the bonding process and the
required bump dimension:
- thin solder bumps used for thermode bonding
- high solder bumps used for reflow soldering and useful for self-alignment

We are a research institute which offers the process transfer of
electroplating AuSn on different wafer types and the bonding process. We
would like to share with you the informations regarding vendors which
offer AuSn plating solutions.

Best regards,

Hermann

>
> Hi, Friends
>
> I would like to study the Au-Sn solder bumps for electronics
> packaging. Does anyone can recommend a vendor selling Au-Sn
> electroplating solution?
>
> Thank you very much
>
> Zhiyan
>
--
Dr. Hermann Oppermann
Fraunhofer IZM
Gustav-Meyer-Allee 25
D-13355 Berlin, Germany
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phone: +49-30-46403-163, -153 (secr.)
Fax:   +49-30-46403-162
email: oppermann@izm.fraunhofer.de
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Dept. Photonic and Power System Assembly
Group Optoelectronics & RF System Integration
http://www.izm.fhg.de/avt/opperm.htm
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